If I add a new book (I created with my mod) to a book store cell (like Renoits Books in Chorrol) it automatically appears in the owner's (Renoit's) for-sale inventory. The same occurs if a new ingredient is added to the counter of an Alchemist vendor's store.

Does the game engine automatically do this, or is it possibly another mod's script (like Cobl)?? It would have to scan the contents of the cell and add the items to what? The cell owner's vendor container?

It seems like a good idea to keep the vendor's stuff for sale consistent with what is on display. But then I gotta wonder what the vendor's container is for. Adding additional stuff not on display)?

Also, if there is another container in the cell that contains other things, but is not set as the NPC's container, the items still get added to the NPC's sale items? I noticed that there is another container below the floor of Renoits that contains a single scroll, and the scroll is for sale.

Once more thing, if I add the item to the vendor's container (instead of putting it in the cell), it does not appear for sale right away. In this case the game has to reset the vendor for the item to appear? I am thinking the solution is to add the item to the cell where it can't be seen or taken by the PC if I want it to appear for sale right away.

Thanks.

Items placed in the cell but not in containers don't respawn -- if the vendor only sold what was on display, they'd run out of things for sale eventually. The vendor container is also where items sold to the merchant go, so that they don't end up in the vendor's personal inventory.

NPCs will sell whatever is in their current cell (or in containers in that cell) that they own personally (their base actor owns it). If you want to make an item not for sale, you can make it owned by a faction the vendor is a member of.

Vendors also only sell the types of items they're defined as selling in the AI tab, unless the player has 50 Mercantile.